Both of your sentences are correct, but they're both very awkward, because they sound very formal and mathematical and precise, which does not really suit the contents of the sentence. ("Is greater than" and "the degree to which" are not common in conversation.) Here are some more natural ways to express the same idea:
- I enjoyed the movie more than I am disappointed by it.
- I enjoyed the movie, mostly, but am a bit disappointed by it.
The meaning also seems a bit strange — if you enjoyed the movie, then why are you disappointed by it? — but you can fix that by explaining your disappointment:
- I enjoyed the movie, but I'm a little bit disappointed that it dropped some important parts of the book.
- The movie wasn't quite as good as I'd expected, but still, it was pretty enjoyable. I'd recommend it.
- I thought the fight scenes were terrible, but the rest of the movie was good enough to make up for it.
I don't if there are specific rules involved but beginning a non-question sentence with "how much" sounds awkward. According to dictionaries the phrase "how much" is usually used as a question starter or an emphasis on the degree/extent of something.(You have no idea HOW MUCH the city has changed).
There's some truth to this, but I don't think it's a completely accurate description. How much can non-awkwardly start a non-question sentence in at least a few cases, such as:
- exclamatory sentences: "How much you've grown!" (meaning roughly "You've grown so much!")
- when what's relevant is the knowledge, or non-knowledge, of the amount: "How much I make is none of his business" (meaning roughly "I don't want or need to tell him my wage/salary").
And in cases where it is a bit awkward, I don't think that replacing it with "the degree to which" really helps.